The Eye and Vision – How vision works
Vision begins when light enters the eye through the cornea, a powerful focusing surface. The cornea is what gives us clear vision. From there, it travels through clear aqueous fluid, and passes through a small aperture in the iris called the pupil.
As muscles in the iris relax or constrict, the pupil changes size to adjust the amount of light entering the eye. Light rays are bent and focused through the lens, and proceed through a clear jelly-like substance in the center of the eye called vitreous humor, which helps give the eye form and shape. When light rays finally land on the retina, the part of the eye similar to film in a camera, they form an upside-down image. The retina converts the image into an electrical impulse that travels along the optic nerve to the brain, where it is interpreted as an upright image.
This animation above depicts the light rays’ path through the eyeball as they pass through the cornea, the eye’s lens and vitreous and striking the surface of the retina, the back inner “wallpaper” in the globe of the eyeball.
All of these structures of the eye mentioned here are critically important in the process of visual acuity. Any disease or condition that affects any of these eye components can cause vision decrease or loss, or even blindness.
Legal blindness is a very depressing and costly problem in the United States and the rest of the world. Low vision can lead to depression and decrease the ambulatory abilities of its victims. It is important to treat these secondary complications as well as the eye disease or conditions. Eye disease illustrations can be seen here.